This invention relates in general to intermediate transfer members for electrostatic transfer of a toned image, particularly to intermediate transfer members having a top layer of a thermoplastic film forming binder coated onto a bottom film base layer, and processes for preparing the same.
Intermediate transfer members enable a higher reproduction rate for color images using a four color system as compared to those without intermediate transfer members. Furthermore, registration of the final color toner image is improved.
In such multicolor systems, component colors such as cyan, yellow, magenta, and black are synchronously developed onto one or more xerographic imaging members and transferred in registration onto an intermediate transfer member at a transfer station. The composite color image is then transferred to a receiving surface or substrate such as paper.
Intermediate transfer members employed in imaging apparatuses in which a developed image is first transferred from the imaging member to the intermediate transfer member and then transferred from the intermediate transfer member to a substrate should exhibit both good transfer of toner material from the imaging member to the intermediate transfer member and good transfer of toner material from the intermediate transfer member to the substrate. Good transfer occurs when most or all of the toner material comprising the image is transferred and little residual toner remains on the surface from which the image was transferred. Good transfer is particularly important when the imaging process involves generating full color images by sequentially generating and developing images in each primary color in succession and superimposing the primary color images onto each other on the intermediate transfer member, since undesirable shifting or color deterioration in the final colors can occur when the primary color images are not accurately and efficiently transferred from the intermediate transfer member to the substrate.
Examples of an intermediate transfer member can be found in U.S. Pat. No. 5,110,702 which discloses non-electrostatic transfer of a toned image using a roll as an intermediate transfer member, and in U.S. Pat. No. 3,893,761 which discloses an intermediate transfer belt having a polyamide film substrate coated with 0.1 to 10 mils of silicone rubber or a fluoroelastomer.
U.S. Pat. Nos. 4,684,238 and 4,690,539 disclose single layer intermediate transfer belts composed of polyethylene terephthalate or other suitable propylene material.
U.S. Pat. No. 5,119,140 discloses a single layer intermediate transfer belt preferably fabricated from clear Tedlar, carbon loaded Tedlar or pigmented Tedlar.
U.S. Pat. No. 5,099,286 discloses an intermediate transfer belt comprising electrically conductive urethane rubber reportedly having a volume resistivity of 10.sup.3 to 10.sup.4 ohm-cm and a dielectric layer of polytetrafluoroethylene reportedly having a volume resistivity equal to or greater than 10.sup.14 ohm-cm.
Although there are a number of intermediate transfer members employed in imaging apparatuses, there is still a need for intermediate transfer members with improved mechanical strength and electrical properties which enable generation of full color images with high color fidelity.